The present invention relates to a display device using a discharge lamp, and particularly to a display device which is compact in size and light in weight and suitable for displaying characters, numerals, symbols, etc.
Conventionally, since the discharge voltage and current for discharge lamps utilizing a glow-discharge tube such as neon tube are relatively low, such discharge lamps have been widely used for pilot lamps or beacon lamps.
As is well known in the art, since this type of glow discharge lamps is constructed to generate glow-discharge between the electrodes provided within a glass tube, the area of electroluminescence is limited to the vicinity of the electrodes.
To employ this type of discharge lamps for a display device and permit discharge with electro-luminescence substantially throughout the length of the glass tube, the electrodes provided within the glass tube must be made large or formed to a special shape, whereupon the discharge starting voltages becomes remarkably high or the discharge lamp becomes remarkably large.
In addition to the above type of discharge lamps, there is a well known type of discharge lamps, where both of two electrodes are provided outside of the glass tube and the gas charged within the glass tube is indirectly driven to display various information.
To drive the gas charged within a glass tube indirectly and carry out effective electro-luminescence, it is necessary to cover the area proximate to the electrodes with a material having high dielectric constant and also necessary to supply AC power having high frequency and voltage.
The display device utilizing discharge lamps such as neon discharge lamp develops a relatively high luminance upon discharging and various colored lights by suitably selecting gases to be charged in the discharge tube of fluorescent paints to be applied to the inner wall of the discharge tube, and thus it has been widely employed in a display field.
As is well known in the art, since the display device utilizing discharge lamps require a AC power supply having high voltage of several thousand volts or more and high frequency of several ten kilo hertz or more, for example, it is essential to provide a power supplying system including a starting circuit, and further to provide means for preventing an electric shock due to high voltage. As a result, this type of display device using a discharge lamp is usually disposed outdoors and utilized for purposes of advertisement.